1. The Field of the Invention
The present invention is related to an improved joint for connecting two or more segments of a structure. More particularly, the present invention is related to a joint for use in connecting extruded segments to form the body portion of a pressure vessel, such as a tank for storing liquid propane.
2. Technical Background
Pressure vessels are widely used to store liquids and gases under pressure. The storage capacity of a pressure vessel depends on the internal volume of the pressure vessel and the pressure the vessel is capable of safely containing. In addition to its storage capacity, the size, internal shape, external shape, and weight of the pressure vessel are often important.
One growing application of pressure vessels is their use in the storage of alternative fuels, such as propane, for use in vehicles such as automobiles. Propane is increasingly viewed as preferable to gasoline for fueling vehicles. Accordingly, approaches have been devised for converting gasoline-fueled vehicles to propane-fueled vehicles by retrofitting them to use propane instead of gasoline. Additionally, vehicles are now being built which are designed to operate using propane as fuel.
Typical propane storage tanks are cylindrical in shape. Positioning cylindrical storage tanks in the envelope utilized for a fuel tank in most vehicles results in substantial limitations in the amount of propane a vehicle can carry. Hence, storage tanks have been devised which utilize a plurality of arcuate outer wall segments which are connected by internal web segments to form a multi-cell pressure vessel. Such multi-cell pressure vessels have a generally uniform cross section, thereby enabling the outer wall segments to be formed by extrusion.
One disadvantage associated with such multi-cell pressure vessels is the difficulty of obtaining a secure and inexpensive joint for connecting adjacent segments. Typically, adjacent segments are connected by welding them together. One disadvantage to the use of such a welded joint is the high manufacturing cost resulting from welding multiple joints to form a single multi-cell pressure vessel.
Another disadvantage to the use of a welded joint is that welding the joint generally results in heat treating the edges of the wall segments, thereby reducing the strength of the wall segments adjacent the weld. When tested for burst strength, such welded pressure vessels frequently fail in the wall segments that were exposed to the heat from the welding process.
From the foregoing, it will be appreciated that it would be an advancement in the art to provide an improved joint for use in a multi-cell pressure vessel that would be inexpensive to manufacture and assemble.
It would be a further advancement in the art to provide an improved joint for use in a multi-cell pressure vessel which does not suffer from the reduced strength implications arising from heating the pressure vessel during welding.
Such a joint for use in a multi-cell pressure vessel is disclosed and claimed herein.